Cerebrospinal fluid analysis (CSF) is commonly performed in clinical neurology, and is a sensitive, but non-specific indicator of central nervous system (CNS) pathology. Blood contaminated CSF samples have the potential to adversely affect results of cytologic, serologic, microbiologic, and molecular biologic diagnostics. A clear consensus of the effects of blood contamination on CSF analysis could not be drawn following a review of the existing veterinary literature. Based on data from earlier reports, it was hypothesized that iatrogenic blood contamination of CSF would result in significant increases in both the CSF total protein (TP) concentration and nucleated cell count (WBC). As hypothesized, in vitro CSF blood contamination resulted in statistically significant (p < 0.01) linear increases in both the CSF TP and WBC with increasing RBC concentration in CSF from sixteen normal dogs. Although increases in TP and WBC are statistically significant, their clinical impact is negligible. Results of this study demonstrate that in normal dogs, the mean CSF TP concentration collected from the cerebellomedullary cistern, is lower than previously reported. D-dimers are plasminolytic cleavage products formed by the cross-linkage of fibrin by Factor XIIIa. In humans, D-dimer analysis can be used to differentiate iatrogenic from pathologic CNS hemorrhage. An additional objective of this study was to determine if canine D-dimers could be assayed using commercially available latex agglutination (LA) and enzymatic immunoassay (EIA) kits in normal and diseased subjects. It was hypothesized that qualitative and quantitative determinations of blood and CSF D-dimer activities could be aid in the diagnosis of dogs with altered CNS and/or systemic coagulation. D-dimers were able to be assayed in all subjects studied. D-dimer concentrations in CSF samples, when analyzed using a qualitative LA assay system, from healthy dogs with iatrogenically blood contaminated CSF were consistently negative. Quantitation of CSF D-dimer concentrations in normal dogs using an EIA assay resulted in lower values (mean 16.2 + 4.3 ng/ml; range, 0 to 54 ng/ml) than detected in the peripheral blood of dogs and humans (normal cutoff value < 250 ng/ml). These findings suggest that D-dimer formation does not occur in canine CSF freshly contaminated with blood. Significantly (p < 0.001) higher mean blood D-dimer concentrations were present in dogs with systemic coagulation disorders (1,093.4 + 172.3 ng/ml; range, 0 to > 2,000 ng/ml) when compared to normal dogs (54.6 + 19.8 ng/ml; range, 0 to 190 ng/ml), when assayed with the EIA. When used as an adjunct in the diagnosis of systemic coagulation abnormalities, the EIA assay had an overall sensitivity of 92%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value (NPV) of 94%. When applied to the same dogs, the LA D-dimer was less sensitive and specific (sensitivity of 73%, specificity of 100%, PPV of 100%, and NPV of 80%) than the EIA. Evidence of intrathecal fibrinolysis in the absence of systemic abnormalities was also demonstrated using CSF LA and EIA D-dimer assays in some dogs with a variety of infectious (Rocky mountain spotted fever), non-infectious inflammatory (granulomatous meningoencephalitis, steroid-responsive meningitis), traumatic (intervertebral disc disease, spinal fracture), and neoplastic (meningioma) diseases. When all dogs with CNS diseases were examined together, the mean EIA D-dimer concentration was significantly (p = 0.03) higher (511.6 + 279.8 ng/ml) than normal dogs (mean 16.2 + 4.3 ng/ml). Future studies will be required before the definitive role of D-dimer analysis can be defined in veterinary medicine. / Master of Science

L'étude systématique de l'hémostase post-thrombolytique a été peu étudiée. Chez 80 malades thrombolysés consécutifs, une étude prospective a comporté l'étude – aux heures 0, 2 et 24 – des facteurs de l'hémostase suivants: fibrinogène, plasminogène, PDF (produits de dégradation de la fibrine et du fibrinogène), D-dimères, alpha2-antiplasmine et facteur XIII, ainsi que l'hématocrite et la numération plaquettaire. Des calculs statistiques approfondis ont exploré les corrélations des variations des facteurs hémostatiques entre eux et avec 37 paramètres cliniques et étiologiques. Processus moléculaires post-thrombolytiques. Le rt-PA induit deux processus, indépendants statistiquement à la 2ème heure: d'une part une élévation des PDF et des D-dimères; d'autre part, une baisse du fibrinogène, corrélée à une baisse du plasminogène (r=0,48, p=0.01), de l'alpha2-antiplasmine (r=0.48, p =0.004) et du facteur XIII (r=0.44, p=0.01). La baisse du plasminogène est corrélée significativement avec celle de l'alpha2-antiplasmine (r=0.77, p<0.001), et du facteur XIII (r=0.47, p=0.02). La mise en jeu de facteurs anti-fibrinolytiques, qui n'avait jamais été décrite précédemment, peut jouer un rôle dans une limitation de la fibrinolyse et dans la rethrombose. Des corrélations sont notées entre la baisse précoce du plasminogène et l'étiologie cardioembolique (p=0.04), et un mauvais pronostic final (p=0.03), possiblement en rapport la thrombolyse intense de gros caillots. Les hématomes intra-cérébraux parenchymateux (HP) sont liés significativement à la baisse du fibrinogène (p=0.01) et à l'augmentation des PDF (p=0.01). Une baisse du fibrinogène au-dessous de 2g/L multiplie la probabilité de HP précoce par un facteur 12,82. Ainsi est confirmé le modèle d'une “coagulopathie précoce avec dégradation du fibrinogène”», prédictive de l'hématome, proposé par l'équipe lyonnaise de thrombolyse en 2004 / A systematic study of post-thrombolytic haemostasis has rarely been performed. In 80 consecutive patients, we have prospectively studied at hours 0, 2 and 24 the following parameters: fibrinogen, plasminogen, alpha2-antiplasmin, factor XIII, fibrin(ogen) Degradation Products (FDP), D-dimers, haematocrit and platelet count. Comprehensive statistical studies calculated correlations of the haemostatic values betwen themselves and with 38 etiological and clinical parameters. Molecular dynamics. Two changes between h0 and h2 were statistically independent: an increase in FDP and D-Dimers; a decrease in fibrinogen, plasminogen, alpha2-antiplasmin and factor XIII. At h2, the decrease in fibrinogen was significantly correlated with that of plasminogen (0.48, p = 0.01), alpha2-antiplasmin (0.48, p = 0.004), and factor XIII (0.44, p = 0.01). The decrease in plasminogen was significantly correlated with those of antifibrinolytic components, alpha2-antiplasmin (r=0.77, p<0.001) and factor XIII (0.47, p=0.02). To our knowledge, such an activation of antifibrinolytic components had not hitherto been mentioned. The h2 decrease of plasminogen was correlated with cardioembolic etiology (p=0.04) and final poor oucome (p=0.03), a fact possibly due to intense thrombolysis of large clots. Patients having early parenchymal hematomas (PH) showed h2 haemostasis disturbances: high FDP (p=0.01), and low fibrinogen (p=0.01). The decrease in fibrinogen less than 2g/L multiplies the odds of early PH by a factor 12.82. Thus, we confirm the model of an “early fibrinogen degradation coagulopathy” predictive of hematomas, which had been coined by the Lyon thrombolysis team in 2004